In a useful method for the fabrication of color filter elements for solid state electronic color image sensing devices, for example, CCD, CID and MOS devices, dyed filter elements are formed by coating photopatternable layers, imagewise exposing, washing off unexposed layer portions, and then dyeing the remaining filter layer by dye imbibition.
In one approach, hydrophilic colloids, for example, gelatin, can be suspended in water along with a radiation responsive hardening (i.e., crosslinking) agent to Form the photopatternable composition. The hydrophilic colloid can be employed in combination with a dichromate salt employed as the radiation responsive hardening agent.
In another important approach, diazo resins are the photoresponsive polymers for forming the photopatternable composition. The diazo resin can be mixed with a mordant to produce a photopatternable composition employed to form the dyed filter elements. A variety of mordants are known which are compatible with the formation of photopatternable layers by the diazo resin. These approaches are described, for example, in European Patent Application 249,991.
However, these and other approaches have not been entirely satisfactory for a variety of reasons. The photopatternable compositions useful in forming dyed filter elements in solid state color imaging sensors advantageously exhibit a unique combination of properties. For example, the composition desirably exhibits good rheological properties for coatability, good speed, fine resolution, sharp pattern profiles, low scumming, uniform dye uptake and good dye density to thickness ratios. Additionally, it is desirable that the dyed filter element exhibit a low D-min after processing and good thermal and light stability. Moreover, in solid state color imaging sensor applications, it is particularly important that the filter elements be formed of materials that exhibit low absorbance of blue light and have good optical clarity.
Thus, the problem solved by this invention has been to provide a photopatternable composition useful in forming dyed filter elements having good thermal and light stability for solid state color image sensing devices, such composition exhibiting good rheological properties for coatability, good speed, fine resolution, sharp pattern profiles, low scumming, uniform dye uptake, good dye density to thickness ratios, a low D-min after processing and which exhibit less absorbance of blue light and have improved optical clarity than prior art compositions.